<?php
    $a=$_POST['a'];
    $b=$_POST['b'];
	$c=$_POST['c'];
    
	if ($a==0){
		echo "a = 0, enter a";
	}
	$d = ($b * $b) - 4 * $a * $c;
	if ($d == 0){
		$x1 = $x2 = -$b / 2 * $a;
		echo"x1=x2=.$x1.";
	}
	else if($d < 0){
		echo "Koreniv nemae";
	}
	else{
		$x1 = (-$b - sqrt($d))/ (2 * $a);
		$x2 = (-$b + sqrt($d))/ (2 * $a);
		echo ".$x1.$x2";
	}
   
?>